<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    #box{
        width: 200px;
        height: 200px;
        background-color: aqua;
    }
</style>
<body>
    <button onclick="kkk()">变宽</button>
    <button onclick="ggg()">变高</button>
    <button onclick="sss()">变色</button>
    <button onclick="yc()">隐藏</button>
    <button onclick="zzz()">重置</button>
    <div id="box"></div>
</body>
<script>
    var cc=document.getElementById('box')
    function kkk(){
       cc.style.width="500px"
       cc.style.display="block"
       cc.style.backgroundColor="aqua"
   }
   function ggg(){
        cc.style.height="700px"
        cc.style.display="block"
        cc.style.backgroundColor="aqua"
   }
   function sss(){
        cc.style.backgroundColor="red"
        cc.style.display="block"
   }
   function yc(){
        cc.style.display="none"
   }
   function zzz(){
        cc.style.width="200px"
        cc.style.height="200px"
        cc.style.backgroundColor="aqua"
        cc.style.display="block"
   }
</script>
</html>